Coating method, coating layer, and turbine shroud

Abstract

A coating method includes depositing a slurry including a coarsely particulate ceramic and a finely particulate ceramic on a base material configured with an oxide-based ceramics matrix composite such that a proportion of coarse particles decreases towards a surface of the base material; forming a bond coating by performing a heat treatment on the base material on which the slurry has been deposited; and forming a top coating by thermally spraying a ceramic onto the bond coating. The oxide-based ceramics matrix composite is an alumina silica type oxide-based ceramics matrix composite. The coarsely particulate ceramic and the finely particulate ceramic are alumina-based powder.

The invention claimed is: 
     
       1. A coating method comprising:
 depositing a slurry including a coarsely particulate ceramic and a finely particulate ceramic on a base material configured with an oxide-based ceramics matrix composite such that a proportion of coarse particles decreases towards a surface of the slurry, 
 forming a bond coating by performing a heat treatment on the base material on which the slurry has been deposited; and 
 forming a top coating by thermally spraying a ceramic onto the bond coating, 
 wherein the oxide-based ceramics matrix composite is an alumina silica type oxide-based ceramics matrix composite, and 
 the coarsely particulate ceramic and the finely particulate ceramic are alumina-based powder, 
 wherein the depositing includes
 depositing a first slurry in which the coarsely particulate ceramic and the finely particulate ceramic are mixed at a first proportion which has been preset, on the base material, and 
 depositing a second slurry in which the coarsely particulate ceramic and the finely particulate ceramic are mixed at a second proportion having a proportion of coarse particles which is lower than that in the first proportion, on a surface of the first slurry. 
 
 
     
     
       2. The coating method according to  claim 1 , wherein
 a proportion of coarse particles in the first slurry is in a range of 60 vol % to 80 vol %, and 
 the proportion of coarse particles in the second slurry is in a range of 40 vol % to 60 vol %. 
 
     
     
       3. A coating method comprising:
 depositing a slurry including a coarsely particulate ceramic and a finely particulate ceramic on a base material configured with an oxide-based ceramics matrix composite such that a proportion of coarse particles decreases towards a surface of the slurry, 
 forming a bond coating by performing a heat treatment on the base material on which the slurry has been deposited; and 
 forming a top coating by thermally spraying a ceramic onto the bond coating, 
 wherein the oxide-based ceramics matrix composite is a pure alumina type oxide-based ceramics matrix composite, and 
 the coarsely particulate ceramic is a mixture of alumina-based powder and zirconia-based powder and the finely particulate ceramic is a mixture of alumina-based powder and zirconia-based powder, 
 wherein the depositing includes
 depositing a first slurry in which the coarsely particulate ceramic and the finely particulate ceramic are mixed at a first proportion which has been preset, on the base material, and 
 depositing a second slurry in which the coarsely particulate ceramic and the finely particulate ceramic are mixed at a second proportion having a proportion of coarse particles which is lower than that in the first proportion, on a surface of the first slurry. 
 
 
     
     
       4. The coating method according to  claim 3 , wherein
 a proportion of coarse particles in the first slurry is in a range of 60 vol % to 80 vol %, and 
 the proportion of coarse particles in the second slurry is in a range of 40 vol % to 60 vol %. 
 
     
     
       5. A coating method comprising:
 depositing a slurry including a coarsely particulate ceramic and a finely particulate ceramic on a base material configured with an oxide-based ceramics matrix composite such that a proportion of coarse particles decreases towards a surface of the slurry, 
 forming a bond coating by performing a heat treatment on the base material on which the slurry has been deposited; and 
 forming a top coating by thermally spraying a ceramic onto the bond coating, 
 wherein the top coating is a zirconia abradable top coating, and 
 wherein the depositing includes
 depositing a first slurry in which the coarsely particulate ceramic and the finely particulate ceramic are mixed at a first proportion which has been preset, on the base material, and 
 depositing a second slurry in which the coarsely particulate ceramic and the finely particulate ceramic are mixed at a second proportion having a proportion of coarse particles which is lower than that in the first proportion, on a surface of the first slurry. 
 
 
     
     
       6. The coating method according to  claim 5 , wherein
 a proportion of coarse particles in the first slurry is in a range of 60 vol % to 80 vol %, and 
 the proportion of coarse particles in the second slurry is in a range of 40 vol % to 60 vol %.